A very large number of electrical connections may be found inside an integrated circuit. These are formed from conducting materials (such as polysilicon and aluminium) and used for propagating a variety of electrical signals, including power supplies voltages and ground.
Within an integrated circuit, the electric and electromagnetic couplings (between connections, the substrate, and logic and/or analog circuit sections) are quite high due to the very short distances. The couplings may originate noise in the electrical signals. These couplings and the attendant noise must be taken into proper account in the design of the integrated circuit, which is not easily accomplished.